Numerous types of folding tables structures are known in the prior art, including portable tables having folding legs that include locking means for holding the legs in an operative position. Such tables are commonly used by many groups, including assembly and convention halls, hotels, institutions, churches, meeting establishments and the like, that cater to large groups of people. Large portable folding tables, often referred to as "banquet tables", allow the organizations or institutions to tailor the configurations of banquet rooms to the anticipated requirements of the group. In the event that folding tables are not needed for a particular function or event, they can, of course, be stored. Thus, use of folding tables permits such organizations to maximize the effectiveness and utilization of their available floor space and accompanying facilities, while minimizing the storage space requirements for the tables when they are not needed.
Common problems encountered with some prior art tables are that they are fabricated of heavy materials, often requiring two or more persons to handle the tables. Such tables are typically made of fiber or particle board, plywood, or Masonite-type materials, and may also have a Formica type surface laminated onto one of the foregoing underlying materials. Such tables have frequently been made stronger or sturdier by making the table tops thicker and heavier. Attempts to make the table tops thicker and sturdier only exacerbates the bulkiness and weight problem. Such prior art tables may weigh, for example, eighty to ninety pounds or more for a banquet-sized table.
Another drawback with prior art tables such as those discussed above is that the means of attachment of the legs to the table tops often tend to fail or give way prematurely, sometimes pulling completely away from the table top, either ruining it altogether, or necessitating repairs. The repairs often require that additional leg fastening means, such as bolts or the like, extend to the table top, which can be unsightly.
Another problem with such prior art folding tables is that the materials used in the tables are susceptible to water damage. Materials which absorb water, or other liquids coming into contact with them prematurely deteriorate and provide an unsightly appearance. Still another problem with such prior art tables is that they can sometimes splinter if subjected to improper loads, or even after periods of routine use. Such splintering is at least annoying and can be hazardous.
One proposed solution to the prior art problems discussed above is to make parts of the table tops from lightweight metals, such as aluminum. Aluminum tables can be expensive for most organizations and tend to dent easily when subjected to the routine wear and tear and to be noisy in normal use. Such tables can also have sharp edges, posing a hazard, like the splinters of the prior art tables discussed above.
Another proposed solution is the use of plastic materials for such tables. U.S. Pat. No. 3,628,470 to De Luca discloses a portable lightweight foldable support platform comprising a planar support member fabricated of a core of lightweight, high-strength material, such as a balsa wood composition, and having a plastic layer secured to the underside of the core and a nonskid textured plastic layer secured to the upper surface of the core. The longitudinal sides of the core have aluminum rails secured thereto, and the leg assemblies are provided with pivotable hinges to enable them to be folded flat against the underside of the platform for storage.
U.S. Pat. No. 4,951,576, to Cobos et al., discloses a portable plastic folding table. The table structure includes upper and lower plastic table top halves with reinforcing a framework grid sandwiched therebetween. The framework grid is preferably made of wood, and includes joists or beam members interconnected by reinforcing cross members. The framework grid is received in a correlatively-shaped shell integrally formed in the lower plastic half of the table top. Folding legs are mounted on the underside of the table top by using fasteners that pass through the lower plastic half of the table top and a pair of cross members of the framework. The lower table top half is provided with gussets at selected locations between relatively high vertical walls and the adjacent horizontal planar surfaces. Stiffening ribs, which may be extensions of the shell, are also disposed on the lower table top half.
U.S. Pat. No. 4,951,576 further discloses that the reinforcing cross members and joists of their wooden framework are disposed at locations to provide structural support and rigidity to the plastic-sandwiched table top structure, and to provide attachment and positive mechanical support for the folding legs of the table. In assembly, bolts or other fastening means are inserted through the cross members and through the lower plastic half of the table top to permit attachment of support brackets for the legs, prior to affixing the upper plastic half of the table top to the lower plastic half. Support brackets for securing the folding legs to the table are affixed to the bolts or fasteners that extend through lower plastic half of the table top. In the table of the '576 patent, loads imposed on the ends of the table are carried by the plastic lower half of the table and the only stress relief for the ends of the plastic lower half is at the side rails of the framework. Therefore, gusset means are provided in the underside corners of the lower plastic half to maintain its structural integrity. Moreover, the folding leg assemblies must be attached (bolted) to the cross members of the wooden framework to carry the forces imposed by table top loads through the wooden cross members for transfer to the folding legs and to prevent the imposition of possibly destructive stress concentrations on the lower plastic table half by the leg attachment brackets.
Notwithstanding these developments, a need exists for a portable, lightweight yet strong, foldable table structure with improved load bearing characteristics, folding legs and means for readily securing the folding legs to the underside of the table structure.